Monday–Friday, March 5–9, 2018;
Los Angeles, California

Abstract: B11.00012 : Prediction of Thermodynamic Stability of Double-Perovskite Halides: Density Functional Theory Calculations and the Role of Different Exchange-Correlation Functionals*

1:51 PM–2:03 PM

Abstract

Presenter:

Tao Zhang(East China Normal University)

Authors:

Tao Zhang(East China Normal University)

Dan Han(East China Normal University)

Menglin Huang(East China Normal University)

Deyan Sun(East China Normal University)

Maohua Du(Oak Ridge National Laboratory)

Shiyou Chen(East China Normal University)

Recently, a set of double-perovskite halide compounds have attracted intensive interests as promising alternatives to CH3NH3PbI3 because they are Pb-free and may exhibit enhanced stability. The thermodynamic stability of lots of double-perovskite halides has been predicted based on density functional theory calculations of compound formation energies. We found that the stability prediction can be sensitive to the exchange-correlation functionals, e.g., the widely-used PBE functional predict that Cs2AgBiBr6 is thermodynamically unstable, obviously inconsistent with the good stability observed experimentally. The incorrect prediction by the PBE functional results from its failure to predict the correct ground-state structures of AgBr, AgCl and CsCl. In contrast, the DFT calculations based on LDA, optB86b-vdW and optB88-vdW functionals can correctly predict the ground-state structures of these binary halides. Furthermore, the optB88-vdW functional is found to give the most accurate description of the lattice constants of the double-perovskite halides and their competing phases. Hence, we suggest that the optB88-vdW functional should be used for predicting thermodynamic stability for new double-perovskite halides.

*This work was supported by NSFC under grant Nos. 61574059 and 61722402.